Squealing is usually a loose drive belt. If it isn't loose, it may indicate that something is not rolling correctly, like perhaps the water pump. Overheating after awhile, especially while at a stoplight, strongly suggests the car's radiator may be plugged and not rejecting enough engine heat. Since you say the water temps slowly increase, I say with certainty that your radiator is probably the culprit. You can test this by emptying all the coolant and filling with water only and drive. If the car does not overheat with water, you know the radiator needs replacement. Plain water has better heat absorption than water/antifreeze mix. It is not a good idea to leave mostly water in the engine as coolant, it will damage the engine.